* {
    margin: 0;
    padding: 0;
}

body {
    background-color: rgb(241, 242, 245);
}

.fl {
    float: left;
}

.fr {
    float: right;
}

.clear::after {
    content: '';
    height: 0;
    display: block;
    clear: both;
}

.mt {
    margin-top: 20px;
}

.mb {
    margin-bottom: 20px;
}

.ml {
    margin-left: 20px;
}

.mr {
    margin-right: 20px;
}